Potential miss-communication between AMD and manufacturing company caused new line of video cards Radeon HD 6790 to have increased number of ROPs. This video card is designed to have only 16 out of 32 active blocks of rasterization in 40 nm technology Barts.
While this, so called, problem is a great advantage for end consumer it's very frustrating for AMD because it slows down line of production for the company.
The "problem" has been recognized by TechPowerUp when their GPU-Z utility displayed 24 ROP instead of 16. Initially, testers thought their utility encountered an error or miss-calculated results but in reality Radeon HD 6790 actually had 24 active ROP. TechPowerUp contacted AMD to confirm this information and it is official that every video card has 24 blocks of rasterization.
This isn't the first time AMD is having these problems. Few Radeon HD 4830 video cards had 80 less processors than expected. Another one, Radeon HD 6850 had 1120 active shader processors instead of 960.